Continuous kiln and method of operating same



Grinnell/Filed July 27@ 1920. 2 Sheets-Sheet 2 II IIIIIIIIIJI I.

j n n c DREssLER cognition# KILNAND us'mon or OPERATING smua-Paieazeailane'm 1925.l y

umrsn s-rArEsrA'rENr Orl-ical Y constan 'nnmumor sumas, omo, a'ssxcnonro Anuamcnl Dnmsmn rusnx'als, nic., Or myosin-n. Y., A CORPORATION Ormaw Yolix.

rcolr'rxmious mn am) nnrnon or orsna'rmo san continuada u'eppneeunsemina. :aanstaan my a7, mao, renewed apra sa, laas. -rn'a 1 opnemen neaaugen 2s, im. seran ne. 734s.

To all whom it l Beit known that ll, Comun DunssLnn, a subject-ofthe:King of Great Britain, and resident of-'Clevelamh in the county of lCuyahoga andrSt-ate of Ohio, have invented rccrtainznewtand usefulImprovements in t Qontinuous Kilns'and Methods of Operating Saine,'. ofwhich the following is a specification.- i ,n l 'i la Y Thegeneralobjectofthc present invention y is to provide kfor thee-ll'ective utilization of acontinuolus tunnel kiln in "heating/articlesto a uniform temperature where,thc rate at which heatil should beimparledto thc articles ll varies from time to time.k v

My inventiamv'was primarily devised for, andis Ofl-"a siecial value inaplant. for casting andro ling aluminum. ln rolling alumiuumiit isdesirable that the billets I should be `delivered to the rolls atalteinperature of about 500 C. lf heatedabove this 'temperature the"'billets approach ytoo closely to the melting point o aluminum,

aturealuxninum does not have the proper duetility. 'lhe billets areformed by castingyand' may be takenjout of the moulds while theirinteriors'are well abovel 500 U.,

. although'their surfacer .temperatures will.' 80 their be lesl than.500 C. In lsuch case',

whilefa billdnniy contain sulcient heat to bring it to an averagetemperature of 5 00O C., it'is necessary to place the billet -in anannealing furnace or soaking pit in which the billet temperature is madeuniform Afrom surface to ntmgbepfore passing the billet to' the roll. f

If each ibilletfcast should be withdrawn from the mould in which it isformed and 40 placed'in the annealing kiln orsoaking pit, whilestilllretainiug heat sullcient to ring the entire billet to the desiredtemperature -for rolling it 'would not necessary to use any fuel inheating'thefurmwe'or soaking '45 pit except ip'erhaps to make upy forsome or all of the haat radiation or other losses from the furnace orlpit. Where the billets are annealed in a continuous tunnel kiln it `isnoty practically "ble,'however, to put so .tu of melbilleeeinu, the ,kankwhile mh billet maintains sacentheaiio" bring the billet to temperaturefor rolling. In tb Ollllition of a continuous tun-l nel kan the billetsmuet be fedrime uw entrance end of the kiln at the same rate as the arewithdrawn from the exit vend of the ki n.y The billets must be passedirrimediately to the rolls. as they ar` withdrawn from the kiln.tolavoid cooling, and the rate 4atwhich the hilly'ctsa-re fed into theentrance. endl of thefkiln thus depends upon-the rate A specific objectof the present-invention is to Vrovide a continuous tunnel kilnconstruction and mode .of Operation whereby billetsanay be properlyannealed at theide'- ysircd temperature of; say 500 C., as fast oraafslowly as is necessary to provide billets riods in whiehthe fortherolls when the operation of the lattcrlis irregular or intermittent,as well as when 1t 1s re ular and contlnuous, and

which will effectively utili-ze the available :elt ed inv-the billetsfed into the h In thc practical carrying out of m invention lem ploy acontinuous tunnel ki -n of the mutlled heated ty and preferably a kilnof` the wcll known lrcssler-ty )c having internal combustion. chambers.or heating the kiln, and provisions for maintaining a directed gravitycirculation of the kiln atmosphere, and suppl heat to or, if necessary,abstract it from the kiln as required to bring the ,billets to theihesired. temperature in .their passage therethrough regardless of the'rate at whichthe billets are passing `through the'kiln or` of theamounts of heat retained by the different billets when introduced intothe kiln. t In the preferred inode of accomplishing this, 1 pass astream/of air i through the kiln chamber from its entra-nce end 'to itsexil and. and then return this air to the entrance end of* naicombustion chambers wherein it is utilized so -far' as ma be required tosupport the combustion o fuel fed into the mufthe kiln through themaillesy or. inter' 3 'y Y i, .1,543,330

am in aie-kan my bowed -in otherways` than that shown, as by elec-'tricity.-' ,L

Infthe preferredmode of o tion contemplated a` ionof the iln chamberaijacent its elivel'yend'ismaintained at,

or approximately atfthe desired annealing above, that .whenbilletscontaining considerable casting hieat .are being' inserted intothe kiln,the frstieiect of the 'air admitted to the' kiln through ythe duct K isto. cool the billets, btfas this`air and the billets travel towardi theexit end of the kiln they y receive heat from the combustion chambersand the pipejextensions H thereof and the apparatus should besooperatedy that a zone o approximately" constant tem krature which isthat at kwhich the bil ets are to be delivered is maintained adjacentthe exit end ofthe kiln. VWhen, as may sometimes happen, tbe hotbillctscontain more than the necessary beat yrequired tokbring therto a uniformdelivery temperature no gas need be supplied to the combustion chambersand in thisvcaseexcess heat Aintroduced into the kiln :the billets and,notr lost by .-.liation froln'the kiln walls' is carried out of Uvkiln`rthrough ythe stackg'I. Under y other con @itions gasi's burnt in 'theVcombusf tion .ch'mbers .att-the yrate required to make l up forradiation losses and for the small loss -oi heat cairied out of the kilnthrough the rate requiredyto make up `for radiation losses and forithesmall loss of heat carried out of the kiln thron 'the stack and thatrequired to bring t e billets up to the delivery temperature. .Y

In'cases 1n which it ls necessary or des1r-` able to anneal the metal inan atmosphere which is neutral or atleast ynot highly oxidizing, suchasan atmosphere of nitrogen, carbon mononide 'orl carbon dioxide, somemmlification of the apparatus shown in Figs. 1 and 2 must' be employed.One simple modification for use under such conditions is illustrated 3and 4.- ,Infthis modification, the groupsof pipes Hl areal-ranged totake up less spaoe,.imeasured transversely ofthe kiln, thantheeonstruction shown in- Figs. l and 2J a vAlongside of each` group oftubes ll is .a second group of'tubes HC conner-ted at their endstoheaders HB and HB2 respectively. Theheader HB' receives air,

i :is from the fan nthrougi; tbe pipes Q', and

the head1-v' lili* connects tooneend of a durf: lll)v inthe;'coiresprmding kiln bench which runsv under the correspondingcombustion chamber for its full length, being I connected to the latteratthe exit end of the kiln bv a port F1". AThe headers HA and HAz towhich the pipes H are connected are arranged and connected as are theheaders H and H2 of the construction first described.

A, pipe provided withl a controlling valve l e leads to the kiln chamberfrom a. gas tank P or other suitable source of supply of the neutral ornon-oxidizing gas which istol form the atmosphere of the kiln:"cliambcr. As shown, the pipe P dischar es into the kiln `chamberthrough a nozzle A like the nozzle K first descrlbed.

the preferred construction shown herein and that my inventlon 1s capableof advantageous .use for other purposes than preparing alu- 1. Themethod of annealing articles pre-l viously heated to differenttemperatures which .consists in passing'the articles through anelongated annealing chamber and supplying heat to, or abstracting itfrom the chamber as'required to maintain the desired annealintemperature in a ipal portion of the kiln and tobringeach article to atempcratureapproximately the same as said desired temperature during thepassage of the article l V`through* the preceding portion ofthechamstark I. Under other conditions ga's is ber burnt in theicombustion chambers at the `to dierent tem eratures which consists infrom the rate at which the billets are cast, which consists in passingthe billets through an elongated annealing chamber and su plying heatto, or abeti-acting it from the c amber as required to maintaincach/billet at an approximately constant annealing temperature during afinal portion of its travel through the chamber, notwithstanding thevariations in casting Iheat retaine'dby the billets when entered in. thechamber, andl It will b e apparent'to those skilled in` -the art that myinvention may be carried out by means of other forms of kiln than- 2:The method of annealing articles heated A healing the billets at a ratevarying at times 'variations in the speed at which the billets are movedthrough the chamber.

4. The method of supplying a variable demand for annealed billets vcastat a rate varying at times from` the rate at which the.

- 5. The method of operating a continuous tunnel kiln comprising anelongated kiln chamber and a combustion chamber therein extending Afromthe exit end of the kiln chamber towards its inlet end which consists inpassing air through the kiln chamber from its inlet end to its exit end,and from the kiln chamber into -the combustion chamber at the exit endof the kiln chamber and supplying fuel to the combustion chamber at itsexit end as' .required tomaintain a uniform temperature in a portion ofthe kiln chamber adjacent its exit end.

6. The method of vannealing billets'at a desired temperature andutilizing casting heat in so doing, which consists in passing thebillets through a tunnelkiln chamber, heating said chamber by an,internal 1Coml bustion chamber located inthe kiln chamber and extendingfrom the exit end toward theentrance end of the kiln chan ing airthrough the 4kiln cha entrance end towards its exit und am into andthrough the combu and supplying'luel to the conber adjacent the enit endel quired to maintain a portion chamber adjacent its enit end. :1temperature.

7. A continuous tunnel in combination an elong combustion chamberextending -a the kiln from the delivery end o toward its entrance end, cfuel to said combustion chamba livery end of the kiln, an. air ilcombustion chamber from the kiln cham at t'he deliveryend of thelat-ter, and niet for passing air into the kilnj clit aber at entranceend.

8. A continuous tunnel kiln comprisiuc' in combination with an elongatedchainh Y combustion chamber extending lengthwise el' the kiln from thedelivery and of the l: ter toward its entrance end, means supplying fuelto said combustion chamber at the livery end of the kiln, and means forsugoH plying air -to said combustion chamber at the delivery end of thekiln including pr@ visions for causing the so supplied to travellongitudinally ci the kiln ch from the entrance end to the deliveryvent. thereoil andtoabstract heat -from "the kiln chamber in its travel.A l

Signed at Cleveland, in the county olf Cuyahoga, and State oi Ohio, this25th day of August, l). i924-,

